1. Field of the Invention
The present invention relates to solid-state relays transmitting signals wirelessly and semiconductor device including the solid-state relays.
2. Description of the Related Art
In a solid-state relay, signals are transmitted without contact between a signal input-side circuit and an output-side circuit controlling power output with the use of a photocoupler or the like including a light-emitting element and a light-receiving element. Specifically, a solid-state relay having a photocoupler includes at least a light-emitting element, a light-receiving element generating electromotive force by reception of light from the light-emitting element, and a semiconductor element whose conduction or non-conduction is selected by the electromotive force. Power is output when the semiconductor element is conducting, and power output is stopped when the semiconductor element is not conducting.
A latching solid-state relay needs power when the conduction or non-conduction of the semiconductor element is changed, whereas the latching solid-state relay does not need power when the conduction or non-conduction of the semiconductor element is unchanged. Thus, power consumption can be reduced. Patent Document 1 discloses a contactless relay that employs photocoupler isolation and has a latching function.